<?php
class JSSDK {
  private $appId;
  private $appSecret;
  public function __construct($appId, $appSecret) {
    $this->appId = $appId;
    $this->appSecret = $appSecret;
  }

  public function getSignPackage() {
    $jsapiTicket = $this->getJsApiTicket();

    // 注意 URL 一定要动态获取，不能 hardcode.
    $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
    $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

    $timestamp = time();
    $nonceStr = $this->createNonceStr();

    // 这里参数的顺序要按照 key 值 ASCII 码升序排序
    $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";

    $signature = sha1($string);

    $signPackage = array(
      "appId"     => $this->appId,
      "nonceStr"  => $nonceStr,
      "timestamp" => $timestamp,
      "url"       => $url,
      "signature" => $signature,
      "rawString" => $string
    );
    return $signPackage; 
  }

  private function createNonceStr($length = 16) {
    $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    $str = "";
    for ($i = 0; $i < $length; $i++) {
      $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
    }
    return $str;
  }
	
	private function getJsApiTicket() {
		// jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例
		if (file_exists(dirname(__FILE__) . "/jsapi_ticket.json")) {
			$data = json_decode(file_get_contents(dirname(__FILE__) . "/jsapi_ticket.json"));
			if ($data->expire_time < time()) {
				$ticket = $this->getJsApiTicketFromWxServer($data);
			} else {
				$ticket = $data->jsapi_ticket;
			}
		} else {
			// $this->getJsApiTicketFromWxServer($data);
			$accessToken = $this->getAccessToken();
			// 如果是企业号用以下 URL 获取 ticket
			// $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
			$url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
			$res = json_decode($this->httpGet($url));
			$ticket = $res->ticket;
			if ($ticket) {
				$arr = array('expire_time'=>time() + 7000, 'jsapi_ticket'=>$ticket);
				// $data->expire_time = time() + 7000;
				// $data->jsapi_ticket = $ticket;
				$fp = fopen(dirname(__FILE__) . "/jsapi_ticket.json", "w");
				fwrite($fp, json_encode($arr));
				fclose($fp);
			}
		}
    
		return $ticket;
	}

	private function getJsApiTicketFromWxServer($jsapi_ticket_data) {
		$accessToken = $this->getAccessToken();
		// 如果是企业号用以下 URL 获取 ticket
		// $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
		$url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
		$res = json_decode($this->httpGet($url));
		$ticket = $res->ticket;
		if ($ticket) {
			$jsapi_ticket_data->expire_time = time() + 7000;
			$jsapi_ticket_data->jsapi_ticket = $ticket;
			$fp = fopen(dirname(__FILE__) . "/jsapi_ticket.json", "w");
			fwrite($fp, json_encode($jsapi_ticket_data));
			fclose($fp);
		}
		
		return $ticket;
	}
	
	private function getAccessToken() {
		// access_token 应该全局存储与更新，以下代码以写入到文件中做示例
		if (file_exists(dirname(__FILE__) . "/access_token.json")) {
			$data = json_decode(file_get_contents(dirname(__FILE__) . "/access_token.json"));
			if ($data->expire_time < time()) {
				// 如果是企业号用以下URL获取access_token
				// $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
				$url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
				$res = json_decode($this->httpGet($url));
				$access_token = $res->access_token;
				if ($access_token) {
					$data->expire_time = time() + 7000;
					$data->access_token = $access_token;
					$fp = fopen(dirname(__FILE__) . "/access_token.json", "w");
					fwrite($fp, json_encode($data));
					fclose($fp);
				}
			} else {
				$access_token = $data->access_token;
			}
		} else {
			// 如果是企业号用以下URL获取access_token
			// $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
			$url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
			$res = json_decode($this->httpGet($url));
			$access_token = $res->access_token;
			if ($access_token) {
				$arr = array('expire_time'=>time() + 7000, 'access_token'=>$access_token);
				// $data->expire_time = time() + 7000;
				// $data->access_token = $access_token;
				$fp = fopen(dirname(__FILE__) . "/access_token.json", "w");
				fwrite($fp, json_encode($arr));
				fclose($fp);
			}
		}
		
		return $access_token;
	}

	private function getAccessTokenFromWxServer() {
		
	}
	
	private function httpGet($url) {
		$curl = curl_init();
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($curl, CURLOPT_TIMEOUT, 500);
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
		curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
		curl_setopt($curl, CURLOPT_URL, $url);
		
		$res = curl_exec($curl);
		curl_close($curl);
		
		return $res;
	}
}
